Part dynamics in the intermediate regime of a linear vibratory feeder

Linear vibratory feeder is one of the most extensively used part feeding systems in a production line. The part motion on the feeder can be sliding or hopping or a combination of these two. Based on the dynamics of part motion this paper identifies three distinct regimes. A mathematical model was developed that can predict the trend in conveying velocity in these regimes. This model can provide the parts position as a function of time and has considered relative displacement between the part and the conveying surface. The simulation was validated by performing experiments for a range of vibration frequencies and amplitudes.

The UV and FTIR Fingerprint of Ocimum kilimandscharicum Guerke Essential oil: A Eugenol-Rich Chemo Type

Ocimum kilimandscharicum Guerke, a member of the family Lamiaceae, is a valuable medicinal plant used both in traditional and modern medicine. It is a perennial aromatic undershrub with tremendous phytochemical polymorphism. The present study aims to assess the amount of eugenol in the essential oil (EO) of O. kilimandscharicum. Eugenol is one of the most popular phenolic compounds, which is naturally synthesized and extracted from the EO of different plant species. The fresh leaves and flowers of O. kilimandsharicum were used to extract EO using a hydrodistillation method. Ultraviolet (UV) and Fourier Transform Infrared (FTIR) spectrometry techniques were used to assess and quantify the chemical fingerprint of the EO and their main phytoconstituents. In this study, eugenol showed its peak absorbance to be around 282 nm in both the EO and pure eugenol spectra. The FTIR spectra of the EO and eugenol showed different functional groups determined by comparing the vibration frequencies in wave numbers of the EO and eugenol spectra with those of an IR correlation chart. Eugenol is a well-known phenolic compound with medicinal and economic value. The UV and FTIR spectra of the EO of O. kilimandsharicum proved the presence of a high amount of eugenol in the O. kilimandscharicum plant.

Transport systems load-bearing structures state diagnistics and monitoring

Aim: To provide the study and control of the stress-strain state of load-bearing structures during the operation of magnetolevitation transport systems. Methods: Experimental and theoretical studies of dynamic parameters. Results: To assess the stress-strain state of the main load-bearing structures of magnetolevitation transport systems using string superstructure it is proposed to measure the natural vibration frequencies. Conclusion: The organization of diagnostics or monitoring of changes in the natural vibration frequencies of load-bearing structures ensures the operational reliability of load-bearing structures for Maglev.

Three-Dimensional Free Vibration Analyses of Preloaded Cracked Plates of Functionally Graded Materials via the MLS-Ritz Method

In this study, the moving least squares (MLS)-Ritz method, which involves combining the Ritz method with admissible functions established using the MLS approach, was used to predict the vibration frequencies of cracked functionally graded material (FGM) plates under static loading on the basis of the three-dimensional elasticity theory. Sets of crack functions are proposed to enrich a set of polynomial functions for constructing admissible functions that represent displacement and slope discontinuities across a crack and appropriate stress singularity behaviors near a crack front. These crack functions enhance the Ritz method in terms of its ability to identify a crack in a plate. Convergence studies of frequencies and comparisons with published results were conducted to demonstrate the correctness and accuracy of the proposed solutions. The proposed approach was also employed for accurately determining the frequencies of cantilevered and simply supported side-cracked rectangular FGM plates and cantilevered internally cracked skewed rhombic FGM plates under uniaxial normal traction. Moreover, the effects of the volume fractions of the FGM constituents, crack configurations, and traction magnitudes on the vibration frequencies of cracked FGM plates were investigated.

A Nonlocal Strain Gradient Approach for Out-of-Plane Vibration of Axially Moving Functionally Graded Nanoplates in a Hygrothermal Environment

Vibration analyses on axially moving functionally graded nanoplates exposed to hygrothermal environments are presented. The theoretical model of the nanoplate is described via the Kirchhoff plate theory in conjunction with the concept of the physical neutral layer. By employing the nonlocal strain gradient theory, the governing equation of motion is derived based on Hamilton’s principle. The composite beam function method, as well as the complex modal approach, is utilized to obtain the vibration frequencies of axially moving functionally graded nanoplates. Some benchmark results related to the effects of temperature changing, moisture concentration, axial speed, aspect ratio, nonlocal parameter, and the material characteristic scale parameter on the stiffness of axially moving functionally graded nanoplates are obtained. The results reveal that with increasing the nonlocal parameter, gradient index, temperature changing, moisture concentration, and axial speed, the vibration frequencies decrease. The frequencies increase while increasing the material characteristic scale parameter and aspect ratio. Moreover, there is an interaction between the nonlocal parameter and material characteristic scale parameter, influencing and restricting each other.

Analysis on the Seismic Performance of Shock Absorption Layer Applied in Tunnel Lining Structure Using Shaking Table Model Tests

Shock absorption layer is a relatively simple and effective aseismic measure, which can bear the adverse effects of surrounding rock deformations and buffer the forces acting on lining structure with seismic action. This paper conducts a series of shaking table model tests to analyze and compare the aseismic performances of tunnel lining structure with and without shock absorption layer in different grades of surrounding rocks, in which the superior thickness of shock absorption layer is determined. Therein, it is concluded that the shock absorption layer has prominent influence on reducing the acceleration responses of surrounding rock and lining structure with seismic excitation. The setting of the shock absorption layer can reduce the acceleration amplitude of tunnel lining with seismic excitation by about half. Furthermore, the setting of 1 cm shock absorption layer will increase the Fourier amplitudes and change the vibration frequencies of surrounding rock and lining structure with seismic excitation, while the setting of 2 cm shock absorption layer can significantly decrease the Fourier amplitudes and keep the vibration frequencies of surrounding rock and lining structure with seismic excitation. Therefore, the aseismic effect of 2 cm shock absorption layer is better than the aseismic effect of 1 cm shock absorption layer, which can both reduce the acceleration amplitude and Fourier amplitude of tunnel lining with seismic excitation while keep its characteristics in frequency domain. This research on the aseismic performance of shock absorption layer can contribute to the construction of tunnel engineering and improve the safety of tunnel lining structure.